External Devices

Question 1

What are barcodes? 2 types?

Answer 1

Printed diagrams that consist of light and dark portions and contain information which cam be read by a computer using a barcode reader
1D and 2D

Question 2

How do barcode readers work?

Answer 2

Consist of a laser light source, a lens, photodiode and a mirror
1. The mirror directs light from the laser onto a printed barcode
2. The light reflected by the barcode passes through the lens and is incident on the photodiode which turns light into electrics, charge
3. This electrical charge can be measured and processed to form a digital signal representing the content of a barcode
4. Light portions of a barcode reflect the most light while dark sections absorb incident light and the pattern of light and dark stripes in a barcode corresponds to binary 1’s and 0s

Question 3

How can we check if the barcode is read correctly?

Answer 3

Have error detection such as parity bits and check digits